Stereoselective Electrophilic Cyclizations of δ-Aminoalkenes Derived from Carbohydrates; Synthesis of Polyhydroxypiperidines

Abstract

Electrophilic cyclizations of a carbohydrate-derived δ-aminoalkene were studied. Iodocyclizations proceeded with moderate steric control to afford the D-gluco-configured piperidine as the major product. More extensive studies with mercuric salts resulted in the definition of new reaction conditions for aminomercuration that give higher, reversed stereoselection. The aminomercurations were also amenable to the use of a range of mercuric salts. These aminomercurations may be under chelation control with substrate allylic benzyloxy substituents. The configurations of the piperidine products were confirmed by elaboration of one bromomercurial to a known aminoalditol by oxydemercuration and hydrogenolysis.